Thermal/alkaline pretreatment of waste activated sludge combined with a microbial fuel cell operated at alkaline pH for efficient energy recovery

Abstract

Energy and resource recovery from waste activated sludge (WAS) is promising for WAS treatment. Microbial fuel cell (MFC) is an environmentally friendly technology for energy recovery from WAS. Low hydrolysis rate and high methanogenic activity of WAS restrained the efficient electricity production in MFC operated at neutral pH. In this study, a combination of thermal/alkaline sludge pretreatment (140 °C, pH 12.5, 40 min) with MFC was developed, aiming to achieve high electricity generation and sludge reduction. Results show that a high power density (1.24 W/m2) was obtained in the MFC operated under alkaline condition. Complete restriction of methane production was achieved using the supernatant of thermal/alkaline pretreated WAS as substrate. 49.0 ± 3.4% of chemical oxygen demand (COD) was removed in the MFC. A low external resistance was favorable for COD removal and the accumulation of electricigens. This work provides a promising strategy for efficient sludge reduction, enhanced energy and resource recovery, as well as reduced greenhouse gas emission.